Generally, light emitting diode (LED) forms minority carriers (electrons or electron holes) injected using the P-N formation of a semiconductor; which has advantages of speed, low power consumption and long durability; and these are recombined to emit light. The present invention has an advantage of saving power as it requires 1/10 of power consumption compared to the previous lamps.
Especially for parts requiring a great amount of power consumption such as traffic lights and street lights, power saving can be maximized if the light emitting diode replaces sodium and mercury which are commonly used in the lights.
But, even though the above light emitting diodes are widely used, for example in an electric sign, it has problems, such as, its brightness not being high enough the fulfill the required lighting standard of a street light or lamp, lacking stability as the brightness is easily affected by surrounding temperature.
To overcome the above problems, developments of new light emitting diodes are in progress and a new power light emitting diode of high brightness is developed. The above power light emitting diode is suitable for street lights due to high brightness compared to the previous light emitting diodes, but emitting heat reaches 200? when switched on, and the caused heat shortens of durability of the light emitting diode and causes separation of the light emitting diode from the connecting clamp due to melting of soldered joint.
Therefore, to lengthen the durability of the above power light emitting diode and to stabilize the brightness, the emitted heat needs to be cooled to keep room temperature.
To prevent and cool the emitted heat above, an air-cooled system was installed to lamps using power light emitting diode, but the air-cooled system failed to overcome the above problems as the cooling effect was unsatisfactory and stability of the temperature was not obtained.
To overcome the above problems, a water cooling system is previously invented. The previous invention comprises of a heat insulator installed on the surface of the substrate with a light installed. The heat transferring part of the above heat insulator is formed of a passage for refrigerant (cooling water), a refrigerant entrance and a refrigerant exit, so that when refrigerant is provided through the refrigerant entrance, the refrigerant circulates the passage inside the heat insulator to absorb the heat of the light, so that the surrounding temperature of the lamp light is decreased due to the cooling water.
But the above previous invention stores the refrigerant separately to the above lamp light which complicates the formation of the device and increases the manufacturing cost. Also, because the cooling system is of a one-sided formation, it cannot provide cooling water of a suitable temperature when the temperature of the cooling water is increased due to the emitted heat from the power light emitting diode, which causes change in temperature of power light emitting diode and in stability of brightness. Therefore, even though stability of brightness and cooling effect is initially achieved, the brightness and cooling effect are gradually decreased due to temperature change